Download Rendering

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HAPTEX
Meeting in Pisa, April 10-12
WP2- Research and Development
of the haptic renderer
- Rendering 11-04-2005
Institute of Applied Systems Computer
Graphics Division
Table of Contents
• Project Architecture
• Structure and Tasks
 Haptic Renderer
 Tactile Renderer
• Work plan for the year
11-04-2005
Institute of Applied Systems Computer
Graphics Division
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The Haptic Renderer
3
Tactile
Device
Visual
Renderer
Physical/
Geometrical
Model
Haptic
Renderer
Haptic
Device
11-04-2005
Institute of Applied Systems Computer
Graphics Division
The Haptic Renderer
Force
Gross
Physical
Model
Small Scale
Surface
Model
11-04-2005
14…25Hz
Force
Haptic
Renderer
Position
(Force)
Height
Function,
Kawabata
4
300…1000Hz
Haptic
Device
Position
(Force)
Tactile
Renderer
drive signals
Tactile Array
Institute of Applied Systems Computer
Graphics Division
Haptic Renderer
• Obtaining information from the force
feedback device
 force, joint positions, contact area
• Computation of reaction forces between
simulation cycles
11-04-2005
Institute of Applied Systems Computer
Graphics Division
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Computation of forces
Compensation of update rates is needed
Possible Solutions:
• Extrapolation of forces
• Predictive local geometry
11-04-2005
Institute of Applied Systems Computer
Graphics Division
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Results of different
extrapolation methods1
constant
time linear
position linear
1Picinbono,G
11-04-2005
et al. “Extrapolation: a solution for FF…”, VR and Prototyp., 1999
Institute of Applied Systems Computer
Graphics Division
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Predictive Local Geometry1
Operations within
each simulation cycle:
• Collision Detection
• Local model computation based on the
predicted user’s motion
• Using Local Model for Proxy-Force
calculation in servo loop
1Park,
JG et al. “Haptic Rendering with Predictive …”, Proc. HAPTICS’04, 2004
11-04-2005
Institute of Applied Systems Computer
Graphics Division
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Tactile Renderer
• contact information
 surface velocity
 position and orientation in texture space
 type of fabric at contact
• fetching physical data of the fabric
(from small scale surface model)
• Building up drive signals for vibro-array
on the basis of a perception function
11-04-2005
Institute of Applied Systems Computer
Graphics Division
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Anatomy of the human skin
mechanical stimulus
rapidly adapting
(RA) receptor
slow adapting
(SA) receptor
11-04-2005
Institute of Applied Systems Computer
Graphics Division
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Receptor Properties
Receptor
Type
Threshold
Rate of
Receptive Field
frequency2 [Hz] Adaption
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Function1
Merkel Disks
0.4 – 1.5
SA-I
Small, well
defined
indentation,
curvature
Ruffini
Corpuscles
250 – 300
SA-II
Large, indistinct
Static force,
skin stretch
Meissner
Corpuscles
1.5 – 50
RA-I
Small, well
defined
Velocity, edges,
Slip detection
Pacinian
Corpuscles
50 – 250
RA-II
Large, indistinct
Acceleration,
vibration
1Johnson,
KO “The roles and functions …”, Curr. Op. in Neurobio., 2001
GA et al. “A four channel analysis …”, Somat. & Mot. Res. 2002
2Gescheider,
11-04-2005
Institute of Applied Systems Computer
Graphics Division
Dimensions in tactile
Texture Perception1
•
•
•
•
•
Smooth – rough
Hard – Soft
Slippery – Sticky
Flat – Bumpy
Warm – Cool
1Hollins,
Dimension 1
Dimension 2
M et al. “Perceptual dimensions …”, Perc. & Psych. , 1993
11-04-2005
Institute of Applied Systems Computer
Graphics Division
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A model of roughness
fractal dimension of surfaces as
measure of roughness
11-04-2005
Institute of Applied Systems Computer
Graphics Division
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Synthesis of fractal surfaces
using Brownian motion
Index H of a Brownian motion
controls the covariance of the increments
11-04-2005
Institute of Applied Systems Computer
Graphics Division
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Perceived roughness
Correlation between fractal dimension
and perceived roughness
Index H
(fract. Dim. = 3 - H)
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Institute of Applied Systems Computer
Graphics Division
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Summary
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• Component Diagram
• Haptic Renderer
 Extrapolation of Forces
 Restriction to Local Geometry
• Tactile Renderer
 Roughness and Softness are dominant dimensions
 Receptors innervating the hand have different
sensitivities and functions for tactile perception
 Mathematical model to control roughness
11-04-2005
Institute of Applied Systems Computer
Graphics Division
Participation in the
next months
• development of a preliminary haptic
renderer (expected Oct 05)
• scientific investigation of tactile
perception (until Jul 05)
• development of an appropriate
perception model (May 05 – Nov 05)
• mapping of physical data
(Oct 05 – Mar 06)
11-04-2005
Institute of Applied Systems Computer
Graphics Division
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